I have run into many pieces of tourmaline rough that appear to be well-shaped to cut an emerald cut with great weight retention, but they have an awkward length to width ratio. I generally shy away from this kind of rough because of technical problems in both cutting and polishing. But if the rough has beautiful color or bands of color like a bi-color I will do my best to balance the colors and retain the largest gem with beautiful color. Less exceptional material is either ground shorter or split to facilitate the finishing of usually much smaller gems with commensurate weight loss.
The rest of this post is a tale of finishing an emerald cut with a width of 5mm and a length of 15mm. The water-worn rough had been in my possession for years without being cut. It was completely frosted and was pale in color except for a principal axis core of orange. The orange had a decent tone level and I had purchased at least three similar pieces from the same dealer. The first two times I had attempted to cut a stone, the material had broken as soon as I attempted to grind it. In normal times I might never have tried to work with this tourmaline again. But the pandemic has made it difficult to get rough and maybe it would hold together. And an off-hand comment of a goldsmith I am beginning to work with about liking large ratio gemstones contributed to keeping me from cutting up the crystal.
The first effort with any emerald cut is getting the preform correctly positioned on the dop stick. With such a thin piece of rough there was not much room for the dop stick to be attached. The preform’s nascent table must also be perpendicular to the dope stick so I have enough to cut the gemstone. The final requirement in positioning the rough on the dope stick is having its long axis line up with the index of the faceting machine. The use of a cheater that can rotate the stone and the acceptance of any correctly positioned index greatly facilitates the process. If this sounds like a lot of fiddling before you ever start cutting you are right.
As I began to grind the stone I am pleased to find that it is both completely stable and well-positioned. The meeting of my facets is good and I complete the grinding of the pavilion without incident, But now comes polishing and you better have a flat polishing lap. Movement of the dipstick in the handpiece can also cause problems but without a really flat lap you will have difficulties with your meets and no flat facets. Fortunately, I have a new lap that is very flat and can do the job if I have the discipline and patience to follow nature’s path. There is a lot more leverage in a long emerald cut and pushing too hard makes the dop stick rock and roll. That is not music to my soul and I have to back off and study the zen of polishing long thin facets again. Refreshed again, I accept my fate as a natural consequence of man’s nature and slowly and deliberately polish out all those stubborn grind marks.
Was all this extra effort worth it? It did make a bright interesting gem and maybe the goldsmith will make a happy setting for it, but I am exhausted. My equipment was pushed to its limits and need practically constant adjustments during the polishing process. I don’t think I will be cutting a similar stone for a long time and I am happy for now to be cutting a few standard round brilliants.